From 030600f9b3c4f9265fcaed97ae81b41ad2d7f7f4 Mon Sep 17 00:00:00 2001
From: Christian Clauss <cclauss@me.com>
Date: Tue, 10 Sep 2019 07:49:07 +0200
Subject: [PATCH] Update matrix_class.py (#1175)

---
 matrix/matrix_class.py | 45 +++++++++++++++---------------------------
 1 file changed, 16 insertions(+), 29 deletions(-)

diff --git a/matrix/matrix_class.py b/matrix/matrix_class.py
index 2cd43fc9c..c82fb2cf6 100644
--- a/matrix/matrix_class.py
+++ b/matrix/matrix_class.py
@@ -102,15 +102,15 @@ class Matrix:
 
     def __init__(self, rows):
         error = TypeError(
-            "Matrices must be formed from a list of zero or more lists containing at least one and the same number of values, \
-                each of which must be of type int or float"
+            "Matrices must be formed from a list of zero or more lists containing at least "
+            "one and the same number of values, each of which must be of type int or float."
         )
         if len(rows) != 0:
             cols = len(rows[0])
             if cols == 0:
                 raise error
             for row in rows:
-                if not len(row) == cols:
+                if len(row) != cols:
                     raise error
                 for value in row:
                     if not isinstance(value, (int, float)):
@@ -137,9 +137,7 @@ class Matrix:
 
     @property
     def is_square(self):
-        if self.order[0] == self.order[1]:
-            return True
-        return False
+        return self.order[0] == self.order[1]
 
     def identity(self):
         values = [
@@ -168,9 +166,7 @@ class Matrix:
             )
 
     def is_invertable(self):
-        if self.determinant():
-            return True
-        return False
+        return bool(self.determinant())
 
     def get_minor(self, row, column):
         values = [
@@ -218,9 +214,8 @@ class Matrix:
         return Matrix(values)
 
     def inverse(self):
-        if not self.is_invertable():
-            return None
-        return self.adjugate() * (1 / self.determinant())
+        determinant = self.determinant()
+        return None if not determinant else self.adjugate() * (1 / determinant)
 
     def __repr__(self):
         return str(self.rows)
@@ -283,14 +278,10 @@ class Matrix:
     def __eq__(self, other):
         if not isinstance(other, Matrix):
             raise TypeError("A Matrix can only be compared with another Matrix")
-        if self.rows == other.rows:
-            return True
-        return False
+        return self.rows == other.rows
 
     def __ne__(self, other):
-        if self == other:
-            return False
-        return True
+        return not self == other
 
     def __neg__(self):
         return self * -1
@@ -316,23 +307,20 @@ class Matrix:
         )
 
     def __mul__(self, other):
-        if not isinstance(other, (int, float, Matrix)):
-            raise TypeError(
-                "A Matrix can only be multiplied by an int, float, or another matrix"
-            )
-        if type(other) in (int, float):
+        if isinstance(other, (int, float)):
             return Matrix([[element * other for element in row] for row in self.rows])
-        if type(other) is Matrix:
+        elif isinstance(other, Matrix):
             if self.num_columns != other.num_rows:
-                raise ValueError(
-                    "The number of columns in the first matrix must be equal to the number of rows in the second"
-                )
+                raise ValueError("The number of columns in the first matrix must "
+                                 "be equal to the number of rows in the second")
             return Matrix(
                 [
                     [Matrix.dot_product(row, column) for column in other.columns()]
                     for row in self.rows
                 ]
             )
+        else:
+            raise TypeError("A Matrix can only be multiplied by an int, float, or another matrix")
 
     def __pow__(self, other):
         if not isinstance(other, int):
@@ -360,5 +348,4 @@ class Matrix:
 if __name__ == "__main__":
     import doctest
 
-    test = doctest.testmod()
-    print(test)
+    doctest.testmod()